Democratic heliocentric coordinates underestimate the rate of instabilities in long-term integrations of the Solar System

Fuente: arXiv
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Auteurs principaux: Rein, Hanno, Dey, Kavi, Tamayo, Daniel
Format: Preprint
Publié: 2026
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author Rein, Hanno
Dey, Kavi
Tamayo, Daniel
author_facet Rein, Hanno
Dey, Kavi
Tamayo, Daniel
contents Wisdom-Holman (WH) integrators are symplectic operator-splitting methods widely used for long-term N-body simulations of planetary systems. Most implementations use either Jacobi coordinates or democratic heliocentric coordinates (DHC) for the Hamiltonian splitting, resulting in slightly different algorithms. In this paper we report results from numerical experiments, which show that integrations of the Solar System using DHC coordinates with typical timesteps of a few days suppress instabilities of the planet Mercury. We further show that this is due to an eccentricity dependent artificial numerical precession introduced by the DHC splitting. While the DHC splitting converges to the correct results at shorter timesteps of ~0.6 days, we argue that Jacobi coordinates remain reliable to significantly longer timesteps when orbits become moderately eccentric, and are thus a better choice when the innermost planet can reach high eccentricities.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08019
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Democratic heliocentric coordinates underestimate the rate of instabilities in long-term integrations of the Solar System
Rein, Hanno
Dey, Kavi
Tamayo, Daniel
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
Wisdom-Holman (WH) integrators are symplectic operator-splitting methods widely used for long-term N-body simulations of planetary systems. Most implementations use either Jacobi coordinates or democratic heliocentric coordinates (DHC) for the Hamiltonian splitting, resulting in slightly different algorithms. In this paper we report results from numerical experiments, which show that integrations of the Solar System using DHC coordinates with typical timesteps of a few days suppress instabilities of the planet Mercury. We further show that this is due to an eccentricity dependent artificial numerical precession introduced by the DHC splitting. While the DHC splitting converges to the correct results at shorter timesteps of ~0.6 days, we argue that Jacobi coordinates remain reliable to significantly longer timesteps when orbits become moderately eccentric, and are thus a better choice when the innermost planet can reach high eccentricities.
title Democratic heliocentric coordinates underestimate the rate of instabilities in long-term integrations of the Solar System
topic Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2601.08019